1. Technical Field
The present invention relates to an image forming apparatus and an image forming method of forming an image by developing an electrostatic latent image formed on a latent image carrier with a charged toner carried in a toner carrier.
2. Related Art
In an image forming apparatus and an image forming method where an electrostatic latent image on a latent image carrier is developed as a toner image and the toner image is transferred to a transfer medium, since a transfer efficiency from the latent image carrier to the transfer medium is 100% or less, a small amount of toner may remain on a surface of the after-transferring latent image carrier. In addition, generally, a toner (so-called fogging toner) adhered to a non-image portion of the electrostatic latent image, to which any toner is not originally to be adhered, is also not transferred but remains. In order to remove such a remaining toner, in a general image forming apparatus, a cleaning member is designed to abut the surface of the after-transferred latent image carrier (refer to JP-A-2006-091566). In addition, as another example, JP-A-2007-316135 discloses a technology where charges are suitably applied to the remaining toner on the latent image carrier and the remaining toner is electrostatically recovered into a developer by a developing roller that abuts the latent image carrier.
Such a remaining toner occurs when an image forming process is performed. Therefore, in the configuration of removing the remaining toner, a consumed amount of a wasteful toner that does not contribute to the image forming is increased. In addition, in the configuration of recovering the remaining toner into the developer, such waste of toner does not occur. However, a deteriorated toner after being used is increased in the developer, so the image quality may be gradually reduced.
In addition, recently, in order to implement a highly accurate image, a high speed process, and a low fixing temperature, it has been considered to employ a toner having a smaller diameter than that of a currently-provided toner. In the toner having such a small diameter, due to an increase in a mirror image force or a van der Wall's force, an adhesive force of the toner to the latent image carrier is larger than that of the toner having a large diameter. Therefore, it is difficult to remove the remaining toner from the latent image carrier. Particularly, an AC jumping developing scheme where the latent image carrier and the toner carrier are disposed to face each other without contact and the development is performed by flying the toner by using an alternating electric field, during the reciprocating movement of the micro-diameter toner, the toner is trapped in the latent image carrier by the aforementioned force, and thus, the toner having a charged polarity that is originally not to be adhered is adhered to the latent image carrier. Therefore, the problems of the occurrence of ground fogging and the increase in the toner consumption caused by the fogging become very serious.